Efficient and knowledgeable biostatistical support is crucial to the proper design and interpretation of research in the biomedical sciences. The principal objective of the Biostatistics Core will be to provide the Thyroid cancer investigators a centralized resource for statistical expertise. Statistical issues will be addressed at all levels of investigation: from the design of experiments, to the integration of data sources and maintenance of data quality, and from descriptions of modeling to inferential statements required for accurate dissemination. In support of this objective, the specific aims of the Biostatistics Core include: 1. To collaborate with project investigators in the formulation of hypotheses and hypotheses testing strategies for all mouse and cell line experiments, and in the design of prognostic/diagnostic, linkage, and micro-array studies. 2. To conduct and direct the statistical analysis of data generated by project investigators including: descriptive summary statistics, error modeling, experimental data inference and decision making, analysis and data preparation for linkage and microarray studies, and prognostic/diagnostic equation modeling and accuracy estimation. 3. To ensure that statistical principles associated with: modeling nuisance or block effects, minimizing inference errors (Type I and II error) by correcting for multiple comparisons and multiple measures, randomizing conditions properly, and decreasing measurement error are employed in all studies. 4. Provide data transfer, management, and integration services that ensure high integrity, security and investigator accessibility. 5. To collaborate with Core A (Clinical Data) and Core B (Mouse) directors to ensure the above principles are used in obtaining valid and reliable data from fully powered and unbiased study designs. 6. To coordinate the development and investigation of newer statistical methodologies, when needed, to directly support ongoing research.